/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.websocket.pojo;

import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.websocket.WrappedMessageHandler;

import javax.websocket.EncodeException;
import javax.websocket.MessageHandler;
import javax.websocket.RemoteEndpoint;
import javax.websocket.Session;
import java.io.IOException;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;

/**
 * Common implementation code for the POJO message handlers.
 *
 * @param <T> The type of message to handle
 */
public abstract class PojoMessageHandlerBase<T>
		implements WrappedMessageHandler {

	protected final Object pojo;
	protected final Method method;
	protected final Session session;
	protected final Object[] params;
	protected final int indexPayload;
	protected final boolean convert;
	protected final int indexSession;
	protected final long maxMessageSize;

	public PojoMessageHandlerBase(Object pojo, Method method,
	                              Session session, Object[] params, int indexPayload, boolean convert,
	                              int indexSession, long maxMessageSize) {
		this.pojo = pojo;
		this.method = method;
		// TODO: The method should already be accessible here but the following
		// code seems to be necessary in some as yet not fully understood cases.
		try {
			this.method.setAccessible(true);
		} catch (Exception e) {
			// It is better to make sure the method is accessible, but
			// ignore exceptions and hope for the best
		}
		this.session = session;
		this.params = params;
		this.indexPayload = indexPayload;
		this.convert = convert;
		this.indexSession = indexSession;
		this.maxMessageSize = maxMessageSize;
	}

	protected final void processResult(Object result) {
		if (result == null) {
			return;
		}

		RemoteEndpoint.Basic remoteEndpoint = session.getBasicRemote();
		try {
			if (result instanceof String) {
				remoteEndpoint.sendText((String) result);
			} else if (result instanceof ByteBuffer) {
				remoteEndpoint.sendBinary((ByteBuffer) result);
			} else if (result instanceof byte[]) {
				remoteEndpoint.sendBinary(ByteBuffer.wrap((byte[]) result));
			} else {
				remoteEndpoint.sendObject(result);
			}
		} catch (IOException ioe) {
			throw new IllegalStateException(ioe);
		} catch (EncodeException ee) {
			throw new IllegalStateException(ee);
		}
	}

	/**
	 * Expose the POJO if it is a message handler so the Session is able to
	 * match requests to remove handlers if the original handler has been
	 * wrapped.
	 */
	@Override
	public final MessageHandler getWrappedHandler() {
		if (pojo instanceof MessageHandler) {
			return (MessageHandler) pojo;
		} else {
			return null;
		}
	}

	@Override
	public final long getMaxMessageSize() {
		return maxMessageSize;
	}

	protected final void handlePojoMethodException(Throwable t) {
		t = ExceptionUtils.unwrapInvocationTargetException(t);
		ExceptionUtils.handleThrowable(t);
		if (t instanceof RuntimeException) {
			throw (RuntimeException) t;
		} else {
			throw new RuntimeException(t.getMessage(), t);
		}
	}
}
